Sanchez has been in power for a month after overthrowing his conservative predecessor Mariano Rajoy in a key parliamentary vote he won with the help of Catalan separatists.
Sanchez has urged Catalan separatist leaders to “turn the page” after Torra said he wanted another referendum on independence.
At the start of this month, six of the nine Catalan leaders held near Madrid were transferred to Catalonia to ease tensions ahead of Monday's talks in Madrid.
They include former Catalan vice president Oriol Junqueras, Jordi Sanchez and Jordi Cuixart of two pro-independence associations and Raul Romeva, the former Catalan government's international affairs chief.
Accused of rebellion along with deposed Catalan leader Carles Puigdemont for their role in the region's proclamation of independence in October 2017, they face up to 25 years in jail.
Torra said the aim of the talks was to “find out the Socialists' view on the right of self-determination for Catalans.”
The government has already rebuffed this with spokeswoman Isabel Celaa responding that the “right to self-determination does not exist in the constitution”.
But a senior Catalan government official told AFP that they would bring this up at Monday's meeting, which starts at 0930 GMT.
“Our proposal to resolve this is a referendum on self-determination. If they have a better idea, they can explain that to us,” the official said.
Catalonia's separatist government pushed ahead with an independence referendum on October 1 despite it having been ruled unconstitutional by the court and Spain's central government. The referendum was followed by a unilateral declaration on independence on October 27.
At the time, separatist authorities said 92 percent of the 2.2 million Catalans who cast their ballot — 43 percent of eligible voters — opted for independence.
The conservative Spanish government in power at the time, headed by Mariano Rajoy, responded by sacking the Catalan government, suspending its parliament and imposing direct rule over the wealthy northeastern region.
Madrid ended direct rule over Catalonia last month after Torra's administration was sworn in.
Catalan lawmaker Meritxell Batet who was recently sworn in as Spain's minister for public administration said the ruling Socialists wanted to amend the constitution to move toward a “federal model”.
However with only 84 deputies in the 350-member house, the Socialists have little room for manouevre.
Amending Spain?s constitution requires a two-thirds majority of the Congress of Deputies.
Sanchez “will not launch anything that is too complicated for such a minority party”, said Fernando Vallespin, a political science professor at the Autonomous University of Madrid.
“There's no majority in Spain for an amendment of the constitution. The right can block it.”
Vallespin said the only possible positive outcome would be if both sides accept to try and reach a compromise that grants Catalonia a special status within Spain with more power over taxation and other matters.
“Sanchez will push for Catalonia to start abiding by the law again and function as a region within the constitution and Torra will say that's not his intention,” Vallespin predicted.
“He wants to walk out saying he asked for a referendum.
“Torra is dogmatic, radical, even more radical than (Carles) Puigdemont.”
The Catalan parliament is divided between moderates and radicals like the exiled Puigdemont, who view any concession towards Madrid as treason.
There are no great expectations from Monday's meeting.
“Things will not be resolved in one or two or three meetings… they have to continue a dialogue,” the senior Catalan official said.
Torra himself has asked Sanchez for a second date in September in Barcelona, Catalonia's main city.
A man holds a placard reading 'Free political prisoners' during a protest called by Catalan pro-independence demonstrators
Sanchez has urged Catalan separatist leaders to 'turn the page'